Valveless devices for pulsatile fluid flow

ABSTRACT

Described are pumps structured for moving fluids with pulsatile flow. The pumps lack valves and pistons and provide pulsatile flow through the gentle rotation of a single, one-piece, sliding vane. The vane is situated inside a slot of a rotary cylinder positioned in a hollow central opening of a housing. Generally, the vane makes minimal contact with the walls of the housing. A gap positioned between the vane and the walls and provides pulsatile fluid movement through the pump with low shear stress on the fluid. Also described are fluidic systems connected to the pumps and methods of operating the pumps and systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication No. 63/065,876 filed Aug. 14, 2020, which is herebyincorporated by reference in its entirety.

FIELD

The present invention relates to the field of devices providingpulsatile fluid movement or circulation.

BACKGROUND

Heart failure, the final common pathway of all forms of heart disease,has a high prevalence domestically and globally, and is on the rise [1].Mechanical circulatory support (MCS) devices, such as ventricular assistdevices (VADs) and the total artificial heart (TAH), [2, 3, 4, 5], haveemerged as approved frontline therapy, providing restoration of failingcirculation, as either a bridge to transplantation, or an alternative totransplantation as destination therapy. Mechanical circulatory supportsystems, such as ventricular assist devices, are the last option for thepreservation of life in cases of manifested cardiac insufficiency wherea patient “needs a heart pump”. Heart assistance systems take over apart, or all, of the pumping work and thereby stabilize circulationuntil a donor organ is available.

Initial MCS designs largely relied on pulsatile membrane-baseddisplacement systems, for both VAD and TAH design. These systemsrequired a drive mechanism which was initially pneumatic with cumbersomehoses and air supplies. Analogous to a real human heart to producepulsatile physiologic flow to the circulatory system, the firstgeneration of VADs (e.g. Berlin Heart EXCOR, Thoratec HeartMate, AbiomedAB5000) and the only FDA approved TAH, SynCardia TAH [20], adopts fixedvolume displacement fashion that incorporates sacs, diaphragms or pusherplates actuated pneumatically, electrically or mechanically. Bloodenters and is pulled into a flexible chamber from left or rightventricle and pushed out into the ascending aorta or pulmonary arterywhile uni-directional blood flow is guaranteed by prosthetic valves.Although they could generate pulsatile physiologic blood flow, thesepumps 1) inherently are bulky which makes them difficult to fit intomany patients [21], 2) have large blood contacting surfaces whichrequire frequent anti-coagulation/antithrombotic use including:warfarin, aspirin and dipyridamole to maintain high internationalstandard ratio (INR) [22], and have potential mechanical failures causedby flexible membranes or diaphragms fatigue [23].

To circumvent the disadvantages mentioned above, second generation VADswere developed (e.g. Thoratec HeartMate2, Reliant Heart HeartAssist5,Berlin Heart INCOR), which are small profile hydrodynamic blood pumpthat generate continuous flow instead of pulsatile flow. These secondgeneration VADs normally include fast spinning impellers (5000-10000RPM), flow straighteners, and diffusers. Due to their working principle,the flowrate depends on the pressure difference across the VAD, whichrequires precise sensors and cardiovascular models and controlalgorithms to generate desired blood flows. However, the dramaticallyhigh velocity at the impeller edge, and via other geometric features ofthese devices contributes high shear stress to blood, inducing hemolysisand platelet activation [23]. Also, thrombus may form in regions ofrecirculation or stagnation, such as the stationary flow straightener[23].

The third generation of VADs (e.g. Thoratec HeartMate3, HeartWare HVAD)and some TAHs (e.g. BiCACOR TAH, Cleveland SmartHeart TAH), utilizingcentrifugal pumping architecture, use lower pump speeds (5000 RPM) dueto higher hydraulic efficiency. Generally, blood enters into the rotorand is driven outward centrifugally to the aorta or pulmonary arterywithout the need for flow straighteners at the inlet or diffusers at theoutlet, thus lowering the probability to induce hemolysis and plateletactivation. Still, noticeably high shear stresses, thus leading to blooddamage, are generated inside these pumps [15, 16, 17].

Compared with normal rotary VADs, rotary piston pumps generate pulsatileflow under a dramatically reduced motor speed, which theoreticallyresults in reduced complications and lowered shear stress. A wankel-likeVAD [14], a wobbling disk VAD [25], a spherical gerotor TAH [26], aspherical rolling disk TAH [27], and the commercially available TorvadVAD are examples of rotary piston pumps. Despite, the capability ofthese designs to generate a pulse, they suffer from the same issues asthe above detailed rotary continuous flow and centrifugal VADs in thatthey impart high shear stress, turbulence, sound, heat and otheractivation forces to blood; and contain areas of stagnancy as well—allof which drive thrombosis.

There remains a need for devices capable of moving critical fluids,biological fluids, including blood, in pulsatile flow and with reducedshear stress and effects.

It is an object of the invention to provide improved pumps and systemsfor pulsatile fluid flow.

It is another object of the invention to provide improved methods forachieving pulsatile fluid flow, particularly with biological fluids.

SUMMARY

Described are pumps, devices, and systems structured for moving fluidswith pulsatile flow. The pumps lack valves and pistons. Generally, thepumps provide pulsatile flow through the gentle rotation of a single,one-piece, sliding vane. The vane is located inside a slot of a rotarycylinder positioned in a hollow central opening of a housing. Generally,a gap is positioned between a majority of the surface area of an end ofthe vane and the walls of the housing to ensure an opening is locatedbetween the vane and the walls. The movement of the vane pushes thefluid in a pulsatile fluid flow through the pump with minimal shearstress on the fluid.

Typically, the valveless pumps for pulsatile fluid flow include: (i) ahousing with a central circular opening defined by a peripheral wall;and (ii) a single vane within the central opening. Each of a fluid inletand a fluid outlet are in fluid communication with the central opening.

The vane is typically configured to rotate about an axis offset from acentral axis of the central circular opening without substantiallycontacting the peripheral walls of the housing. Typically, the vane is asingle, unitary piece with a first end and a second end located atopposite sides of the vane. A gap separates at least a portion andgenerally a majority of the surface area of each of the vane ends fromthe peripheral wall. The gap may be about 10 μm to 5 mm long, asmeasured from the portion of the proximal vane end that is the greatestdistance from the peripheral wall along a horizontal line to theperipheral wall.

A motor can be operably connected to the vane. The motor may be anelectric motor, an electromagnetic motor, a passive magnetic motor, anactive magnetic motor, a hydraulic motor, acoustic motor, or any otherpropulsive means utilized to drive the motor, operably connected to thevane. The motor is typically operably connected to a rotary cylinder.The rotary cylinder includes a slot configured to slidably receive thevane in the slot.

Also described are devices and systems containing the pumps. The systemsinclude the pumps and an inlet port and an outlet port. Generally theinlet port is reversably connected to and in fluid communication with afluid supply tube, and the outlet port is reversably connected to and influid communication with a fluid exit tube.

The pumps, devices, and systems are configured to pump at rotationspeeds between about 10 and 500 rotations per minute with an outputbetween about 0.1 LPM (liters per minute) and about 12 LPM and apressure difference between about 1 mmHg and 220 mmHg During pumping, asthe vane rotates in the clockwise or counterclockwise direction, theflowrate varies, such as in the range of about 1 LPM to about 4 LPM(clockwise rotation) or in the range of about −1 LPM to about 4 LPM(counter clockwise rotation).

The pumps, devices and systems are typically configured to provideconstant fluid displacement volume in the range between about 5 mL perrevolution and about 70 mL per revolution at variable flow rates andvariable fluid pressure.

The system may be a closed system configured to provide circulatoryfluid flow.

The system may include two or more pumps, where each pump is configuredto provide a fluid displacement at variable flow rate and variable fluidpressure.

Also described are methods of operating the pumps and systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are diagrams showing the working principle of the singlevane pump. Left arrow: inlet port, right arrow: outlet port. Diagonalshaded area: low pressure, small checkered area: high pressure, largecheckered area: middle pressure.

FIGS. 2A and 2B are diagrams showing the displacement calculation (FIG.2A) and the instantaneous flow rate calculation (FIG. 2B).

FIG. 3 is a graph showing change in flow rate ([m³/sec]) as arelationship of shaft angle ([rad]). Instantaneous flowrate and aninherent pulsatile flow at a constant rotary speed is shown.

FIGS. 4A-4E are diagrams showing an exemplary pump 100 and itscomponents. FIG. 4A is a side perspective view of pump 100 showing motor90 above motor case 80 contacting the housing 70 and port 60 with inletport 62 and outlet port 64. FIG. 4B is a front perspective view of pump100. FIG. 4C is an exploded view of the pump. The pump 100 includesmotor 90, motor case 80, and housing 70 formed of upper case 40, lowercase 30, and flow straightener 50. The housing 70 includes a centralopening 42 and peripheral walls 44. A rotary cylinder 20 with vane 10are housed in the central opening 42. The rotary cylinder 20 and thevane 10 are operably connected to the motor via shaft 92. The housing 70and contacts the port 60 with inlet port 62 and outlet port 64 throughflow straightener 50. FIG. 4D is a top elevation view of the pumphousing and the inlet and outlet ports. FIG. 4E is a perspective view ofthe rotary cylinder 20 with vane 10 positioned in a slot 22 of therotary cylinder. The rotary cylinder 20 also includes a contact opening24 passing through a portion of the rotary cylinder 20 for operablyconnecting with motor 90 via shaft 92.

FIG. 5 is a diagram of the system used to test fluid flow. Flowdirection: clockwise: pump 1, flow meter 2, pressure sensor 3 at outlet,pressure sensor 4 at inlet, reservoir 5, motor controller 6, and dataacquisition (DAQ) board 7.

FIG. 6 is a graph of flowrate (LPM) versus Pressure (mmHg) showing HQcurves at five different pump speeds (300 RPM, 250 RPM, 200 RPM, 150RPM, and 100 RPM). The open boxes are data from experimentalmeasurements. Dashed lines are linear data fitting curves.

FIGS. 7A-7F are diagrams showing geometric details of the pump thatresult in leakage pathways. FIG. 7A—gap between the rolling cylinder andflow straightener's flow separator (see box B), FIG. 7B—because thesliding vane has a thickness and rounded ends, the locations where thetwo ends of the vane touch the wall vary along the rounded end as thevane rotates. The length of the sliding vane is shorter than the designvalue d₁+d₂ FIG. 7C—and this results in a gap between the vane and thehousing wall as the vane is near θ=90° position. FIG. 7D shows the vaneat vertical position (θ=0° position). FIGS. 7E and 7F show the differentchambers 41 a, 41 b, and 41 c in the central opening 42, which movebased on the location of the rotating vane 10.

FIG. 8 is a graph of flow rate ([LPM]) versus speed ([RPM]) and acomparison between theoretical (solid line) and experimentaldisplacements of the exemplary pump. Experimental data (open boxes) andlinear data fitting curve (dashed line).

FIGS. 9A and 9B are graphs showing theoretical flowrates versusexperimental flowrates. Top: w=101.9 [RPM], P=26.34 [mmHg]; bottom:w=101.5 [RPM], P=98.45 [mmHg]. Dashed horizontal lines are averageflowrates.

FIGS. 10A and 10B are graphs showing theoretical flowrates versusexperimental flowrates. Top: w=196.2 [RPM], P=27.17 [mmHg]; bottom:w=195.6 [RPM], P=105.5 [mmHg]. Dashed horizontal lines are averageflowrates.

FIGS. 11A and 11B are graphs showing theoretical flowrates versusexperimental flowrates. Top: w=295.6 [RPM], P=33.92 [mmHg]; bottom:w=294.1[RPM], P=121.7 [mmHg]. Dashed horizontal lines are averageflowrates.

FIGS. 12A-12D are front elevation views of single unitary vanes. The gapdefined by the maximum distance horizontal between the peripheral walland the proximal vane end, its length is identified as λ. FIG. 12D is adiagram of a vane 10 with wipers 16.

FIG. 13 is a diagram of a portion of an exemplary system 200 containingtwo pumps 100 stacked together. The pumps 100 may share the same motoror have separate motors (not shown in figure).

DETAILED DESCRIPTION I. Pumps

The pumps described herein address fluid mechanical issues, whichcontribute to observed adverse events limiting overall pump and systemsafety and effectiveness. Specifically, the pumps include a slidingvane, driven electrically and/or magnetically with minimal or no contactbetween the vane and pump walls to provide fluid movement with reducedshear stress.

The pumps impart a lower shear stress to fluids by one or more of thefollowing characteristics: reducing pump speed, eliminating the use ofprosthetic valves, and/or including a gap between the vane and pumpwalls. The pumps provide direct control of desired fluid flow. The pumpsare compact. The pumps are particularly useful for medical devices thatare implanted in a patient, as the compact pump structure and fewoperating elements reduces risk of infection in a patient.

A. Valveless Pumps

Described are pumps for moving fluids with pulsatile flow. The pumpslack valves and pistons and provide pulsatile flow through the rotationof a single, one-piece, sliding vane. Pulsatile flow is achieved even atconstant rotational speeds.

1. Components

The valveless pumps typically include a housing with a central openingand a single, one-piece sliding vane in the central opening. The housingtypically includes a peripheral wall enclosing the central opening. Thevane may be positioned within a rotary cylinder positioned in thecentral opening and containing a slot for slidably receiving the vane.The housing typically includes an inlet and an outlet in fluidiccommunication with the central opening. A motor is operably connected tothe vane and configured to regulate the vane rotation speed.

The structure and operability of the pumps provide gentle pulsatile flowand laminar flow to fluids minimizing shear stress on fluids. Typically,the pumps operate at rotation speeds between about 10 and 500 rotationsper minute, optionally in a range from 10 to 400 rotations per minute,from 50 to 400 rotations per minute, or from 100 to 300 rotations perminute. The pumps provide pulsatile flow at flow rates between about 0.1LPM and about 12 LPM, optionally in a range from about 0.1 LPM to about10 LPM, from about 1 LPM to about 5 LPM, from about 1 LPM to about 4LPM, from about 1 LPM to about 3 LPM, or from 1.5 LPM to about 3 LPMwith no more than 500 rotations per minute (RPM), optionally no morethan 400 RPM or no more than 300 RPM of rotor speed.

An exemplary pump includes the housing 70, the rotary cylinder 20 andthe vane 10 operably connected to the motor 90. FIG. 4A is a sideperspective view of an exemplary pump 100 showing motor 90 above motorcase 80 contacting the housing 70 and port 60 with inlet port 62 andoutlet port 64. The pump can have a length (L), a width (W), and aheight (H). Each of the dimensions can be adjusted, as needed, forspecific applications. By way of example, exemplary pump 100 has alength (L) of about 90 mm, a width (W) of about 60 mm, and a height (H)of about 70 mm FIG. 4B is a front perspective view of pump 100. FIG. 4Cis an exploded view of the exemplary pump. The pump 100 includes motor90, motor case 80, and housing 70 formed of upper case 40, lower case30, and flow straightener 50. The housing 70 includes a central opening42 and peripheral walls 44. A rotary cylinder 20 with vane 10 are housedin the central opening 42. The rotary cylinder 20 and the vane 10 areoperably connected to the motor via shaft 92. The housing 70 andcontacts the port 60 with inlet port 62 and outlet port 64 through flowstraightener 50. FIG. 4D is a top elevation view of the device housingcomponents and the port. FIG. 4E is a perspective view of the rotarycylinder 20 with vane 10 positioned in a slot 22 of the rotary cylinder.The rotary cylinder 20 also includes a contact opening 24 passingthrough a portion of the rotary cylinder 20 for operably connecting withmotor 90 via shaft 92.

a. Housing with Central Opening

The housing may be a once-piece hollow structure with a central opening.The housing may be formed by assembling two or more components, such asan upper case 40, a lower case 30, and a flow straightener 50, to form ahollow structure with a central opening. Typically, the central openingis surrounded by peripheral walls 44 of the housing 70.

The housing typically includes at least one inlet 46 and at least oneoutlet 48, although more than one inlet and/or more than one outlet maybe formed for letting the fluid in and out of the pump. The inlet andthe outlet are openings in the peripheral wall to provide fluidcommunication between the inlet and the central opening and between theoutlet and the central opening. The designations inlet and outlet arefunctional in nature, where the inlet allows fluid to flow into the pumpand the outlet allows fluid to flow out of the pump. However, whether anopening in the peripheral wall functions as an inlet or an outletdepends on the direction that the rotary cylinder is rotating.

The housing may include additional one or more openings foraccommodating connections between the motor and the rotary cylinder. Theconnections may be wire connections.

The housing may be coated with a sealant on its interior surface tofurther reduce stress on fluid and reduce shear stress.

The central opening of the housing typically has a height between about10 and 220 mm, such as between about 10 mm and about 100 mm, betweenabout 10 mm and about 25 mm, or about 18 mm. The central opening may becircular in cross-section and have a radius (R in FIG. 2A) between about10 mm and about 50 mm, between about 10 mm and about 25 mm, or about 18mm. These dimensions are particularly relevant for implantable medicaldevices.

b. Rotary Cylinder

The rotary cylinder is typically positioned within the central openingof the housing. The central axis of the rotary cylinder is offset fromthe central axis of the central opening. The rotary cylinder generallyincludes a contact opening and a slot, such as a through hole.

The contact opening is configured to operably connect the rotarycylinder to a motor. The contact opening typically mates with the motorshaft of the motor. The contact opening may be an indentation, or ashaped hole, such as a D-shaped hole, a star-shaped, oval-shaped,tooth-shaped hole, which is configured to mate with arespectively-shaped motor shaft. The contact opening is typicallypositioned on or about the central axis of the rotary cylinder, does notcontact the slot. The contact opening is separate from the slot.

The slot, such as a through hole, is positioned perpendicular to thecentral axis of the rotary cylinder and runs from one side of theperipheral wall to the opposite side of the peripheral wall of thecylinder and through the central axis of the rotary cylinder. The slottypically has a shape that conforms to the shape of the vane, whileallowing the vane to slide within the slot.

Typically, the rotary cylinder has a radius (r in FIG. 2A) between about5 mm and about 30 mm, such as between about 5 mm and about 15 mm, orabout 10 mm. The central axis of the rotary cylinder is offset from thecentral axis of the central opening by a value e (eccentricity, e inFIG. 2A). Typically, e is a value between about 2 mm and about 45 mm,between about 2 mm and about 20 mm, or about 8 mm. These dimensions areparticularly relevant for implantable medical devices.

A rotary cylinder 20 with a contact opening 24 and slot 22, with asingle, one-piece sliding vane 10 shown therein, is depicted in FIG. 4E.

c. Vane

Typically, the pump contains a single vane. The vane is a one-piecevane, positioned in and in slidable relation with the through-hole ofthe rotary cylinder. The vane typically has two opposing ends positionedproximal to the peripheral wall of the housing, and two opposing lateralsurfaces. The opposing ends may have different geometries along alongitudinal plane, but generally are rounded at the edges along atransverse plane.

The lateral surfaces are typically smooth and slide through thethrough-hole contacting the inner walls of the through-hole.

The lateral surfaces may include a raised section proximal to the endsof the vane to act as stoppers. The raised sections may be in any shapethat protrudes from the lateral surfaces. The raised sections may bepositioned proximal to the ends of the vane to prevent the vane fromsliding out of the through hole. The presence of the raised sections isparticularly useful in those in embodiments where the ends of the vanedo not contact the peripheral wall of the housing.

Typically, the vane has a length (d₁+d₂ of FIGS. 2A and 2B) betweenabout 10 mm and about 60 mm, between about 20 mm and about 40 mm, suchas about 36 mm. These dimensions are particularly relevant forimplantable medical devices. However, the vane may have any suitablelength and shape selected to provide a desired level of leakage betweenchambers of the housing. For example, the vane shape and length may beselected to provide more or less leakage between housing chambers. Asnoted below, the vanes may be selected to have a gap with a distance λfrom about 10 μm to 5 mm, optionally from 10 μm to 100 μm, from 100 μmto 1 mm, or from 1 mm to 5 mm.

In some embodiments, the vane may be configured to have an adjustablelength within the housing. The length of the vane may be adjusted withsprings, screws, stoppers, or gears. In these embodiments, the vane isnot a single, one-piece vane, and may include two or more pieces.

The vane is generally operably connected to the motor via the rotarycylinder.

Minimal Contact with the Wall

The vane can have a variety of different geometries. Exemplary differentgeometries to the vane 10 are presented in FIGS. 4E and 12A-12D.Typically, the vane makes minimal contact with the peripheral wall ofthe housing when in a resting position and in use, operates withoutsubstantial contact with the peripheral wall.

The gap between the peripheral wall 44 and the proximal vane end 12 isshown as region 18. The maximum distance measured along a horizontalline between the peripheral wall 44 and the proximal vane end 12 isshown by the distance λ (see, e.g. FIGS. 12A-12C). The distance λ may befrom about 10 μm to 5 mm, optionally from 10 μm to 100 μm, from 100 μmto 1 μm, or from 1 mm to 5 mm, long.

The minimal contact surface is typically equivalent to between about0.01% and 5% of vane's surface area, such as from about 0.01% to 1%,from about 0.01% to 0.5%, or from about 0.01% to 0.1%. Thus, whenrotating in use, the vane operates without substantial contact with theperipheral wall. The minimal contact surface between the vane and theperipheral wall is sufficient to guide the vane as it rotates, such asat rotation speeds between about 10 and 500 rotations per minute,optionally in a range from 10 to 400 rotations per minute, from 50 to400 rotations per minute, or from 100 to 300 rotations per minute.

FIG. 7D shows the different chambers 41 a, 41 b, and 41 c in the centralopening 42 defined by the location of the vane 10 and the peripheralwall 44. The fluid in chamber 41 a is able to mix with fluid in chambers41 b and 41 c due to the gaps between the vane ends 12 and 14 and theperipheral wall 44 as well as due to the gap between the rotary cylinder20 and the peripheral wall 44 showing in FIG. 7B.

Wipers

In some embodiments, the vane includes one or more wipers at each of itsends. In these embodiments, the one or more wipers contact theperipheral wall of the housing, while allowing fluid to flow through thegap between the end of each vane and the peripheral wall. The wipers maybe of any elongated shape. The wipers are typically flexible and able tobend and move along the wall as the vane rotates.

An exemplary vane 10 with wipers 16 is shown in FIG. 12D.

d. Inlet and Outlet

The pump includes an inlet and an outlet in fluid communication with thecentral opening. The inlet and the outlet may be openings in the flowstraightener that are connected to the central opening. FIG. 7C showsthe inlet 46 and the outlet 48 when the vane rotates clockwise. Thedesignations inlet and outlet are functional. The direction of pump flowmay be reversible. For example, if the direction of the vane rotationreverses and the vane rotates in a counterclockwise direction, the inletmay function as an outlet, and the outlet may function as an inlet.

The inlet and the outlet may be of any suitable shape and dimension toprovide desired volume of fluid flow into and out of the pump,respectively. The dimensions of the inlet and the outlet may vary toprovide a pressure difference for the fluid pressure at the inlet and atthe outlet. The typical pressure differences achieved at the inlet andthe outlet are between about 1 mmHg and about 220 mmHg, such as betweenabout 5 mmHg and 200 mmHg, between about 5 mmHg and about 50 mmHg,between about 50 mmHg and about 200 mmHg, or about 5 mmHg, about 10mmHg, about 15 mmHg, about 20 mmHg, about 60 mmHg, about 90 mmHg, about100 mmHg, about 120 mmHg, about 150 mmHg, about 200 mmHg, or about 220mmHg. For example, the pump may generate a pressure head between 60 mmHgand 140 mmHg at 6 LPM or between 10 mmHg and 40 mmHg at 6 LPM.

Typically, the inner diameter of the inlet and the outlet are in therange between about 5 mm and about 20 mm, between about 10 mm and about15 mm, such as about 12.7 mm. The cross-sectional area of the inlet andthe outlet is typically in the range between about 18 mm² and about 320mm², such as about 75 mm² and about 180 mm², such as about 126.68 mm².These dimensions are particularly relevant for implantable medicaldevices.

The pump may also include a flow straightener positioned about the inletand outlet and forming a portion of the housing. A port may enclose theflow straightener and contact the housing. The port may include an inletport in fluid communication with the pump inlet and an outlet port influid communication with the pump outlet.

e. Motor

In some embodiments, the pump includes a motor positioned proximal tothe housing. The motor is operably connected to the rotary cylinder. Theterm “operably connected to the rotary cylinder” refers to a directconnection or an indirect connection between the motor and the rotarycylinder. A direct connection may include a motor shaft configured tomate with the contact opening of the rotary cylinder. The indirectconnection may include the motor contacting one or more elements otherthan the rotary cylinder, such that the one or more elements transferthe motor-generated rotary motion to the rotary cylinder.

The motor, which is operably connected to the rotary cylinder, is thusalso operably connected to the vane. The rotation of the rotary cylindercontrols the rotation of the vane.

The motor may be an electric motor, an electromagnetic motor, a passivemagnetic motor, or an active magnetic motor, hydraulic motor, acousticmotor, or involve other propulsive means for generating motion, operablyconnected to the vane. The motor may include magnetic bearings andreceive electrical signals for controlling the magnetic bearings.Additional magnetic bearing(s) may be positioned on rotary cylinder.

The motor may control axial force of a magnetic axial bearing of therotor.

The motor may be in feedback connection with one or more sensors.

Sensors for various physiological variables, such as fluid temperatureand pressure, may be arranged in the region of the pump. Also, the motormay be in feedback connection with a sensor for the accelerationmeasurement, which gives information with regard to a movement of thepatient, and a sensor that detects the angular position of the rotor inthe pump.

The rotary position sensor may be useful with use of a magnetic bearingin order to determine the axial rotor position. This may form an inputvariable for the control of the bearing and thus the magnetic mountingof the rotor.

2. Scalability

The dimensions of pump components may vary based on pump's use andpurpose. Pumps designed for pulsatile flow of biological fluids may havedimensions given herein. Pumps designed for pulsatile of non-biologicalmay have dimensions of elements scaled up to accommodate their use inindustrial settings. For example, pump and component dimensions asdescribed may be scaled up by a factor of 1.5, 2, 3, 4, 5, 6, 7, 8, 9,10 or more to accommodate pulsatile flow of fluids in food and beverageindustry.

For example, pumps with output of 60 LPM (instead of 6 LPM) with agentle pulsatile flow to fluids may be formed by scaling the pump andits component dimensions by a factor of 10.

3. Function

Typically, the pumps are useful for moving fluids by pulsatile flow. Thepumps are gentle on fluids, minimizing fluid shear stress. Typically,the pumps operate at a rotation speeds between about 10 and 500rotations per minute, optionally in a range from 10 to 400 rotations perminute, from 50 to 400 rotations per minute, or from 100 to 300rotations per minute, and flow rate between about 0.1 LPM and about 12LPM, optionally in a range from about 0.1 LPM to about 10 LPM, fromabout 1 LPM to about 5 LPM, from about 1 LPM to about 4 LPM, from about1 LPM to about 3 LPM, or from 1.5 LPM to about 3 LPM. The pumps canachieve a pressure different at the inlet and the outlet of betweenabout 1 mmHg and 200 mmHg, optionally between about 5 mmHg and 200 mmHg,between about 5 mmHg and about 50 mmHg, or between about 50 mmHg andabout 200 mmHg Typically, the pumps provide fluid displacement atvariable flow rates and variable fluid pressure. The fluid displacementvolumes of the pumps range between about 5 mL per revolution and about70 mL per revolution, optionally from about 5 mL per revolution to about50 mL per revolution, from about 10 mL per revolution to about 50 mL perrevolution, or from about 10 mL per revolution to about 30 mL perrevolution.

Exemplary fluids include incompressible fluids, fluids that have adensity and viscosity of biological fluids, colloids, crystalloids, oremulsions. Preferably, the fluid is blood.

The fluid shear may be measured by methods known in the art. The methodsinclude mathematical modeling and computational fluid dynamics (CFD)simulations, which may be used to predict fluid shear stress byutilizing digitally modeled fluid domain geometry, flow rate andviscosity parameters. The shear stress may be expressed as force perunit area of the pump's internal surface (e.g. Pa, dynes/cm²). The shearstress in pump may be compared to shear stress in tubing with smoothsurfaces, and the difference expressed in percentage increase.

In embodiments where the fluid to be pumped is blood, in vitro hemolysistests and/or shear-mediated platelet activation (SMPA) assay may be usedto assess the level of fluid shear (Berk et al., Artificial Organs,43:870-879 (2019); Li et al., Artificial Organs, 44:E226-E237 (2020)).Assessing SMPA by platelet activity state (PAS) assay can utilizegel-filtered platelets (GFP) isolated by filtration of platelet-richplasma. GFP is typically diluted and passed through the pump at adesired flow rate and samples are taken at timed intervals. Aprothrombinase-based platelet activation state assay may be used tomeasure platelet activation in the sample(s). The value of plateletactivation in the test sample(s) may be compared to the value ofplatelet activation obtained from a negative control sample (anundisturbed sample), as well as to the value of platelet activationobtained from a positive control sample (fully sheared sample).

Shear-mediated platelet activation may be measured utilizingphosphatidylserine externalization [PSE] and Annex V binding, or othermeans as detailed by Roka-Moiia et al., identifying shear vs. othermeans of activation (Roka-Moiia et al., Thrombosis and Haemostasis,120:776-792 (2020)).

Another method that can be used to assess the level of fluid shearincludes measuring plasma-free hemoglobin (PFH) and obtaining NormalizedIndex of Hemolysis (NIH) in blood samples obtained at time intervalsfrom blood passed through the pump (Berk et al., Artificial Organs,43:870-879 (2019)).

Typically, the pumps and systems pump the fluid in a manner thatachieves no more than 15% increase in fluid shear over fluid shearobserved for a negative control, or no greater increase in fluid shearthan 15% increase over fluid shear at baseline (a measurement obtainedwithout pumping initiation). Preferably, the fluid shear obtained withthe disclosed pumps is between about 0.1% and about 15%, between about0.1% and about 10%, or between about 0.1% and about 5%, greater thanfluid shear observed at baseline. Expressed in terms of shear stress,overall shear stress by the pump may be configured to not induceactivation of the traversing fluid. For example, when fluid is blood,the shear stress is no more than optimal of 0-30 dynes/cm², andtypically is less than 70 dynes/cm². Further, the design and control mayalso modulate and control the level of shear stress-accumulation. Forexample, accumulation of shear stress over time (shear stress x time),can be controlled to achieve non-activating passage, pumping andtraverse of fluid.

B. Pumps and Devices

1. Mechanical Circulatory Support (MCS) Devices

Mechanical circulatory support (MCS) devices, i.e. ventricular assistdevices (VADs), ventricular replacement devices, and total artificialhearts (TAHs), while effective and vital in restoring hemodynamics inpatients with circulatory compromise in advanced heart failure, remainlimited by significant adverse thrombotic, embolic, and/or bleedingevents. Many of these complications are due to chronic exposure, via theexisting MCS devices, to non-pulsatile flow and high shear stresscreated by the methods of blood propulsion or use of prosthetic valves.

The valveless pumps may be incorporated into devices for circulatoryfluid flow, and may be used as blood flow assist devices. The valvelesspumps provide lower shear stress imparted to blood by reduced pumpoperating speed compared to first, second, and third generation VADs,while achieving the same output. The valveless pumps do not utilizeprosthetic valves, thus diminishing the generation of shear stresscompared to the shear stress typically observed with first, second, andthird generation VADs. The valveless pumps allow direct flowrate controlto generate desired blood flowrate and pulsatile flow profile.

The pumps described herein can be sized to fit into human adult orpediatric patients. The prototype described in the Examples, having thedimensions listed in Table 1, can be modified to be more compact, suchby as having pumps with a thinner wall (e.g., from 5 mm to 3 mm) and ashallower hole (e.g., from 5 mm to 3 mm). The motor could be modified tohave with a longer shaft, and the can counterbore-like hole of the uppercase could be shortened, such as from 10 mm to 5 mm.

The pumps may be connected to any closed loop or open fluid flowcircuits to provide pulsatile fluid flow with reduced fluid shear.

Exemplary closed loop circulatory fluid flow circuits with pulsatileflow include cardiovascular systems, extracorporeal membrane oxygenationsystem, cardiopulmonary bypass system, or hemodialysis systems. One ormore pumps may be connected to patient's circulatory system and functionas VADs or TAHs. One or more pumps may be connected to an extracorporealmembrane oxygenation system. One or more pumps may be connected to acardiopulmonary bypass system. One or more pumps may be connected to ahemodialysis system to aid with fluid flow.

The pumps can be incorporated into a fully implantable VAD or TAH systemthat minimizes the risk of infection for a patient, provides pulsatilefluid flow at reduced operational speeds than what is available for theexisting VADs and TAHs, and reduced fluid shear stress.

2. Other Uses for Valveless Pumps

Exemplary open fluid flow circuits with pulsatile flow include circuitsin dairy milk production, in food manufacturing, such as in processesrequiring a step of gentle fluid movement and/or a step of fluidfermentation, in beer and wine production, in biotechnology andfermentation applications, and in chemical manufacturing requiringmovement of fragile fluids. Fragile fluids include, for example,colloidal fluids, emulsions, and fluids containing microrganisms, cells,cell aggregates, micro/nanocapsules, liposomes and microparticles and/ornanoparticles.

II. Systems

The pumps may be included in a system containing the pump and one ormore flow path elements. The one or more flow path elements areadditional elements configured to link the pump to a flow path and toprovide a fluid flow path. The elements may include a port with an inletport section and an outlet port section, a fluid supply tube, a fluidexit tube, flow path tubing, flow stoppers, flow splitters, and flowconnectors. The connection between the pump and any one of theadditional elements may be reversible or permanent.

Two or more pumps and one or more flow path elements may be combinedinto a system.

The system may provide pulsatile fluid flow to one or more fluid flowpaths. Typically, the two or more pumps in the system are arranged inany suitable manner relative to each other. The pumps may have anysuitable proximal arrangement. In this embodiment, the position of thepumps relative to each other may vary, so long as the pumps are inphysical contact with one another (e.g., the pumps in FIG. 13 are inphysical contact with one another). The pumps may have a distalarrangement. In this embodiment, the pumps are not in physical contactwith one another.

In proximal arrangement or distal arrangement, the pumps in a system aregenerally operably linked through interconnecting flow paths and one ormore motors. The motors may be programmed to operate at the same ordifferent speeds. The speeds may range between about 10 rotations perminute and 500 rotations per minute, optionally in a range from 10 to400 rotations per minute, from 50 to 400 rotations per minute, or from100 to 300 rotations per minute. The pumps in the system may beconfigured to provide an output between about 5 mL per revolution andabout 50 mL per revolution controlled by the one or more motors. Thepumps in the system may be controlled to provide a time-varyinginstantaneous output flow rate by actively controlling the motor speed.

III. Materials for Pumps and Devices

Suitable materials for forming pump and system elements include metalsand natural and synthetic polymers. The metals include grade 5 titanium,titanium alloys, nickel-titanium alloys, cobalt chromium alloys,stainless steel alloys, copper alloys, iron and/or ferrous alloys,nichrome, zinc and galvanized materials, tantalum, kanthal, orcupronickel.

The polymers typically are biocompatible, and includepolydimethylsiloxane (PDMS), polysulfone (PSF), and other materials.PDMS is a versatile elastomer that is easy to mold, and PSF is a rigid,amber colored, machinable thermoplastic. Other suitable materialsinclude biologically stable thermosetting and thermoforming polymers,including polyethylene, polypropylene, polyoxymethylene (POM)—also knownas acetal, polyacetal, and polyformaldehyde, polymethylmethacrylate,polyurethane, polysulfones, polyetherimide, polyimide, ultra-highmolecular weight polyethylene (UHMWPE), cross-linked UHMWPE and membersof the polyaryletherketone (PAEK) family, including polyetheretherketone(PEEK), carbon-reinforced PEEK, and polyetherketoneketone (PEKK).Preferred thermosetting polymers include, but are not limited to,polyetherketoneketone (PEKK) and polyetheretherketone (PEEK).

One or more of the components of the pumps and/or systems can be formedvia stereolithography, soft lithography, laser machining,micromachining, curing, bonding, three-dimensional printing, additivemanufacturing, molding, micromolding, and/or coating.

IV. Methods of Using

The pumps and systems described herein can be used in a variety ofdifferent methods involving the movement of one or more fluids with apulsatile flow profile along a flow path.

The fluids may be Newtonian or non-Newtonian fluids, and includebiological fluids, critical fluids, colloids, crystalloids, emulsions,nutritional fluids, and fluids in dairy, food, pharmaceutical,biotechnology, and beverage industries. In preferred embodiments, thefluids are blood, serum, plasma, colloids, crystalloids, or nutritionalfluids.

The methods typically include flowing a fluid of interest through thedisclosed pumps or systems. The pumps and systems move the fluids withfluid displacement when subjected to variable flow rates and variablefluid pressures.

Typically, the methods include providing a pulsatile flow to the fluidat a flow rate between about 0.1 LPM and about 12 LPM. For example, themethods include pumping the fluid through the pump with a flowrate inthe range from about 0.1 LPM to about 12 LPM, from about 1 LPM to about4 LPM, from about 1 LPM to about 3 LPM, or from 1.5 LPM to about 3 LPM.As depicted in FIG. 3 , even at constant rotational speeds, the flowratevaries during the rotation of the vane. Thus, during a single rotationof the vane, the flowrate can vary from about 1 LPM to about 4 LPM,about 1 LPM to about 3 LPM, or from 1.5 LPM to about 3 LPM. Throughoutrotation of the vane during the pumping method, the flowrate can varyfrom about 1 LPM to about 4 LPM, or about 1 LPM to about 3 LPM, or from1.5 LPM to about 3 LPM.

The flowrates and flowrate ranges listed above correspond with the vanerotating in one direction, e.g. clockwise direction. However, ifdesired, the vane can reverse direction, and rotate in thecounterclockwise direction. When the flow moves in the reversedirection, e.g. due to the counterclockwise rotation of the vane, thefluid can be pumped through the pump with a flowrate in the range fromabout −0.1 LPM to about −12 LPM, from about −1 LPM to about −4 LPM, fromabout −1 LPM to about −3 LPM, or from −1.5 LPM to about −3 LPM.Similarly, due to the variation in the flowrate during the rotation ofthe vane, during a single rotation of the vane in the counterclockwisedirection, the flowrate can vary from about −1 LPM to about −4 LPM,about −1 LPM to about −3 LPM, or from −1.5 LPM to about −3 LPM.Throughout rotation of the vane during the pumping method for a vanerotating in the reverse (e.g. counterclockwise) direction, the flowratecan vary from about −1 LPM to about −4 LPM, or about −1 LPM to about −3LPM, or from −1.5 LPM to about −3 LPM.

As the direction of the rotation of the vane is able to change from afirst, clockwise direction to a second, counterclockwise direction, theoverall flowrate for the pump can range for example from about −12 LPMto about 12 LPM, from about −8 LMP to about 8 LPM, from about −4 LMP toabout 4 LPM, from about −3 LPM to about 3 LPM.

The methods include pumping the fluid through the pump with a pressuredifference of between about 5 mmHg and 200 mmHg, such as with a pressuredifference between about 5 mmHg and about 50 mmHg, or between about 50mmHg and about 200 mmHg.

The methods for providing pulsatile flow of fluids provides gentlechanges in fluid flow rate resulting in low levels of fluid shearstress. Low level of fluid stress includes fluid stress at between about0 dynes/cm² and about 70 dynes/cm², such as between about 0 dynes/cm²and about 60 dynes/cm², between about 0 dynes/cm² and about 50dynes/cm², between about 0 dynes/cm² and about 40 dynes/cm², betweenabout 0 dynes/cm² and about 30 dynes/cm².

The disclosed pumps, devices, systems, and methods can be furtherunderstood through the following numbered paragraphs.

1. A valveless pump for pulsatile fluid flow comprising:

-   -   (i) a housing with a central circular opening defined by a        peripheral wall;        -   opening; and        -   an inlet in fluid communication with the central circular an            outlet in fluid communication with the central circular            opening; and    -   (ii) a single vane within the central circular opening;        wherein the vane is configured to rotate about an axis offset        from a central axis of the central circular opening without        substantially contacting the peripheral wall of the housing.        2. The valveless pump of paragraph 1, wherein the vane is a        one-piece vane.        3. The valveless pump of paragraph 1 or 2, wherein the vane        comprises two ends and wherein the valveless pump comprises a        gap between each of the two ends and the peripheral wall.        4. The valveless pump of any one of paragraphs 1-3, wherein the        gap is about 10 μm to 5 mm long, optionally from about 10 μm to        100 μm, from about 100 μm to 1 mm, or from about 1 mm to 5 mm        long, as measured from the proximal vane end to the peripheral        wall.        5. The valveless pump of any one of paragraphs 1-4, comprising a        motor operably connected to the vane.        6. The valveless pump of any one of paragraphs 1-5, comprising        an electric motor, an electromagnetic motor, a passive magnetic        motor, or an active magnetic motor, hydraulic motor, or acoustic        motor, operably connected to the vane.        7. The valveless pump of any one of paragraphs 1-6, comprising a        motor operably connected to a rotary cylinder comprising a slot        wherein the vane is slidably received in the slot,    -   wherein a central axis of the rotary cylinder is offset from the        central axis of the central circular opening.        8. The valveless pump of paragraph 7, the slot that runs from        one side of the peripheral wall to the opposite side of the        peripheral wall of the cylinder and through the central axis of        cylinder and has shape that conforms to the shape of the vane.        9. The valveless pump of any one of paragraphs 1-6, comprising a        motor operably connected to a rotary cylinder.        10. The valveless pump of paragraph 9, wherein the rotary        cylinder is configured to rotate about the central axis of the        rotary cylinder.        11. The valveless pump of any one of paragraphs 1-10, wherein        the vane has two ends and wherein each end is rounded.        12. A system comprising the pump of any one of paragraphs 1-11.        13. The system of paragraph 12, further comprising an inlet port        and an outlet port,    -   wherein the inlet port is reversably connected to and in fluid        communication with a fluid supply tube and the outlet port is        reversably connected to and in fluid communication with a fluid        exit tube.        14. The system of paragraph 13, wherein the system is a closed        system configured to provide circulatory fluid flow.        15. The system of any one of paragraphs 12-14, wherein in use        the system is configured to provide constant fluid displacement        volume in a range from about 5 mL to about 70 mL per revolution,        optionally in a range from about 5 mL per revolution to about 50        mL per revolution, from about 10 mL per revolution to about 50        mL per revolution, or from about 10 mL per revolution to about        30 mL per revolution.        16. The system of any one of paragraphs 12-15, wherein in use        the system is configured to provide fluid displacement at        variable flow rates and variable fluid pressure.        17. The system of any one of paragraphs 12-16, wherein the        system comprises two or more pumps of any one of paragraphs        1-11.        18. The system of paragraph 17, wherein each of the two or more        pumps is configured to provide fluid displacement at variable        flow rates and variable fluid pressure.        19. A method for pulsatile flow of an incompressible fluid        comprising pumping the fluid through the pump of any one of        paragraphs 1-11 or through the system of any one of paragraphs        12-18.        20. The method of paragraph 19, wherein the fluid has a density        and viscosity of biological fluids, colloids, crystalloids, or        emulsions, optionally wherein the fluid is blood.        21. The method of paragraph 19 or 20, wherein the pump or system        pumps the fluid into and out of the pump at rotation speeds        between 10 and 500 rotations per minute, optionally in a range        from 10 to 400 rotations per minute, from 50 to 400 rotations        per minute, or from 100 to 300 rotations per minute.        22. The method of any one of paragraphs 19-21, wherein the pump        or system pumps the fluid through the pump at a flow rate        between about −12 LPM and about 12 LPM, optionally in a range        from about −8 LMP to about 8 LPM, from about −4 LMP to about 4        LPM, from about −3 LPM to about 3 LPM.        23. The method of any one of paragraphs 19-22, wherein the step        of pumping the fluid through the pump or system comprises        rotating the vane in the clockwise and/or counter clockwise        direction within the central circular opening.        24. The method of paragraph 23, wherein during rotation of the        van, the fluid flowrate varies, such as from about −12 LPM to        about 12 LPM, from about −8 LMP to about 8 LPM, from about −4        LPM to about 4 LPM, or from about −3 LPM to about 3 LPM.        25. The method of any one of paragraphs 19-24, wherein the        system is a closed circulatory system and wherein the pump pumps        the fluid in a circulatory fluid flow path at a pressure        difference of between about 1 mmHg and 220 mmHg, optionally        between about 10 mm and about 100 mm or between about 10 mm and        about 25 mm.        26. A mechanical circulatory support device comprising a pump        for pulsatile fluid flow comprising:    -   (i) a housing with a central circular opening defined by a        peripheral wall;        -   an inlet in fluid communication with the central opening;            and        -   an outlet in fluid communication with the central opening;            and    -   (ii) a single vane within the central opening;        wherein the vane is configured to rotate about an axis offset        from a central axis of the central circular opening without        substantially contacting the peripheral walls of the housing.        27. The mechanical circulatory support device of paragraph 26,        wherein the device is a ventricular assist device, heart pump,        ventricular replacement device, or a total artificial heart.        28. The mechanical circulatory support device of paragraph 26 or        27, wherein the device is a heart pump, and wherein the pump        generates a pressure head between 60 mmHg and 140 mmHg at 6 LPM        or between 10 mmHg and 40 mmHg at 6 LPM.        29. A method of mechanically supporting a ventricular or heart        function in a subject comprising connecting a pump to the        cardiovascular system of the subject,    -   the pump comprising:        -   (i) a housing with a central circular opening defined by a            peripheral wall;            -   an inlet in fluid communication with the central                opening; and            -   an outlet in fluid communication with the central                opening; and        -   (ii) a single vane within the central opening;    -   wherein the vane is configured to rotate about an axis offset        from a central axis of the central circular opening without        substantially contacting the peripheral walls of the housing.        30. An extracorporeal membrane oxygenation system comprising a        pump of any one of paragraphs 1-11.        31. A cardiopulmonary bypass system comprising a pump of any one        of paragraphs 1-11.

EXAMPLES Example 1. Design of the Non-Compressible Single Sliding VaneMCS Pump

Non-Compressible Single Sliding Vane MCS Pump. The MCS pump, anon-compressible single sliding vane pump, consists of a rollingcylinder (rotor), a sliding vane, case(s), a flow straightener, andports. The rotating cylinder has a through-all slot to allow the vane toslide through completely, and the vane separates the chamber into twocompartments while pumping blood. In one embodiment, the wall geometryof the case (a portion of the housing) is configured to serve as a guidefor one or both of the ends of the vane to slide against. The flowstraightener straightens (a portion of the housing) the flow into andout of the pump and also serves as a guide for the vane to slideagainst.

As the vane has certain thickness, during the sliding motion, the actualcontacting point is not at the tip of the end of the vane (FIG. 7C).Therefore, the actual length of the vane is shorter than the theoreticalvalue obtained by Eqn. 1. When the vane is in a horizontal position(see, e.g. FIG. 7C), the vane is closest to the peripheral wall. Whenthe vane is in a vertical position (see, e.g. FIG. 7D), there is alarger gap between the end of the vane and the housing wall. At otherpositions of the van in the housing, a gap exists between the end of thevane and the peripheral wall.

The vane, the rotary cylinder, and/or the motor guide the vane duringrotation (FIGS. 7C-7F and 12A-12D).

Two chambers are sectioned by the sliding vane and blood is pulled inand pumped out cyclically. As depicted in FIGS. 1A-1D, as the vanerotates, the volume of one chamber decreases and blood is pumped outwhile the volume of the other chamber increases and blood is drawn in.Throughout this process, blood gently pulsates into and out of the MCSwithout need of prosthetic valves, the vane effectively functions as avalve would.

Geometric Design. A parametric equation describes the trajectory of thesliding vane's end-point, which in turn determines the shape of the wallcase.

d ₁(θ)+d ₂(θ)=R+r+e  (1)

where d₁ and d₂ are distances from the two ends of the sliding vane tothe center of the case respectively; θ is the rotating angle of thesliding vane, measured from the vertical position; R is pseudo-radius ofthe case; r is the radius of the rolling cylinder; and e is theeccentricity, as shown in FIGS. 2A and 2B.

With boundary conditions [d₁, d₂]=[R+e, r] at θ=0, [d₁, d₂]=[(R+e+r)/2,(R+e+r)/2] at θ=π/2, and [d₁, d₂]=[r,R+r] at θ=π, one smooth andcontinuous solution to Eqn. 1 is obtained as follows:

$\begin{matrix}{{d_{1}(\theta)} = {{\frac{1 + {\cos\theta}}{2}\left( {R + e} \right)} + {\frac{1 - {\cos\theta}}{2}r}}} & (2)\end{matrix}$

Porting. The chamber volume reaches a maximum when θ=π/2, and in orderto avoid compressing the working fluid, blood, porting starts at thisposition. Ideally porting ends at θ=π because this positionmathematically separates the low- and high-pressure sides. Actual designresults in a little narrow porting size and the porting ends at θ<πbecause wall thickness would occupy some space.

Displacement and Instantaneous Flowrate Calculation. Displacement volumeof existing VADs is vital as a trade-off between overall pump size andpump speed always exists. It can be seen from FIGS. 1A-2B that one fullcycle pumps out four times the shaded volume. The planar area A iscalculated as

$\begin{matrix}{A = {{{\frac{1}{2}{\int_{0}^{\pi/2}{d_{1}^{2}d\theta}}} - {\frac{1}{4}\pi r^{2}}} = {{\frac{1}{32}\left\lbrack {{\left( {R + e} \right)^{2}\left( {{3\pi} + 8} \right)} + {r^{2}\left( {{3\pi} - 8} \right)} + {2{\pi\left( {R + e} \right)}r}} \right\rbrack} - {\frac{1}{4}\pi r^{2}}}}} & (3)\end{matrix}$

Thus, the overall displacement volume per revolution is obtained bymultiplying planar area A and the chamber height h by four.

V _(disp)=4Ah  (4)

The total size of the pump can be obtained similarly:

A _(total)=½∫₀ ^(π) d ₁ ² dθ  (5)

V _(total)=2A _(total) h  (6)

Another feature of the disclosed MCS pump is inherent pulsatility—evenat constant rotational speeds. The instantaneous output flowrate, Q(t),is equal to the change rate of an infinitesimal volume displacement,hdA, and infinitesimal time step, dt:

$\begin{matrix}{{{Q(t)} = {\frac{hdA}{dt} = {\frac{h\left( {{\frac{1}{2}d_{1}^{2}d\theta} - {\frac{1}{2}r^{2}d\theta}} \right)}{dt} = {{\frac{h}{2}\left( {d_{1}^{2} - r^{2}} \right)\frac{d\theta}{dt}} = {{{\frac{h}{2}\left\lbrack {{\left( {R + e} \right)^{2}\cos^{4}\frac{\theta}{2}} + {r^{2}\sin^{4}\frac{\theta}{2}} + {\frac{\left( {R + e} \right)r}{2}\sin^{2}\theta} - r^{2}} \right\rbrack}\overset{˙}{\theta}t} \in \left\lbrack {0,\ {T/4}} \right\rbrack}}}}},\ {T = {2{\pi/\omega}}}} & (7)\end{matrix}$

FIG. 3 plots instantaneous flow rate Q(t) against input shaft angle θ ata constant speed {dot over (θ)}=ω. FIG. 3 shows that the instantaneousflowrate reaches its minimum at θ=(2i+1)π/2 and its maximum at θ=2iπ, i∈

. Therefore, two flow pulses are generated for every revolution (2π) ofthe driving shaft.

Kinematics of Sliding Vane. The kinematics of the sliding vane arederived herein. From Eqns. 1-2, the instantaneous locations of thesliding vane's distal points, P₁ and P₂, are

[P _(1x)(θ)P _(1y)(θ)P _(2x)(θ)P _(2y)(θ)]=[d ₁(θ)sin θd ₁(θ)cos θd₂(θ)sin θd ₂(θ)cos θ]  (8)

The instantaneous location of the center of mass P_(M) and itstrajectory are obtained as follows:

$\begin{matrix}{\left\lbrack {{P_{cx}(\theta)}{P_{cy}(\theta)}} \right\rbrack = \left\lbrack {\frac{\left( {{P_{1x}(\theta)} + {P_{2x}(\theta)}} \right)}{2}\frac{\left( {{P_{1y}(\theta)} + {P_{2y}(\theta)}} \right)}{2}} \right\rbrack} & (9)\end{matrix}$ $\begin{matrix}{{{P_{cx}^{2}(\theta)} + \left\lbrack {{P_{cy}(\theta)} - \frac{R + e - r}{4}} \right\rbrack^{2}} = \left\lbrack \frac{R + e - r}{4} \right\rbrack^{2}} & (10)\end{matrix}$

where the geometric relation ϕ=2θ exists (see FIG. 2B). It can be seenfrom Eqn. 10 that the center of mass of the sliding vane P_(M) forms acircular trajectory around (0, (R+e−r)/4) with radius (R+e−r)/4. Themotion of the sliding vane can be described as a combination of acircular motion of the center of mass at a speed {dot over (ϕ)}=2{dotover (θ)} and a rotation of the rigid body about the center of mass at aspeed {dot over (θ)}.

Design Objectives and Constraints. The first objective is to allow thepump to generate enough output flowrate, Q(t), to satisfy blood demandunder the majority of body conditions. Accordingly, 6 [LPM] is used here[12].

TABLE 1 The design specifications of a prototype. Term Variable ValuePseudo radius R 18[mm] Rolling cylinder radius r 10[mm] Eccentricity e 8[mm] Length of sliding vane d₁ + d₂ 36[mm] Height of pump chamber h18[mm] Displacement volume (per revolution) V_(disp) 24.8[mL]  Innerdiameter of port d_(port) 12.7[mm]  Cross sectional area of port (each)A_(port) 126.68[mm²]  

Example 2. Pump Construction and Experiment Setup

Set Up

A prototype having the specifications described in Table 1 was designed,assembled and tested.

First Generation Prototype. The design of the MCS pump is illustrated inFIGS. 4A-4E. All blood contact parts were manufactured by computernumerical control (CNC) machine with polytetrafluoroethylene (PTFE). Thelower and upper cases have counterbore-like structures to constrain therolling cylinder to rotary motion only. The flow straightener wasdesigned to offer a smooth guide for the vane to slide against. It alsoseparates and prevents the flow path from inlet to outlet. Differentsizes and orientations of the ports are optional to better fitting withcardiac vessels and here a straight configuration with 0.50″ ID wasused. Silicone sealant (GE®) was used to provide further sealing betweenall surfaces. A brushless DC motor (Maxon EC 45) was used as a primedriver, with motor shaft filed to a D-shape profile. A motor case was 3Dprinted by acrylonitrile butadiene styrene (ABS) to fasten the motor andto couple with the pump. A custom-made motor with longer shaft andthinner rotor size may further compact the overall size of the MCS pumpin the future.

Experiment Setup. An experimental loop was constructed using 0.5″ tubingto characterize the MCS pump performance and to demonstrate its inherentflow pulsatility, as shown in FIG. 5 . An industrial grade flow meter(McMaster Part No. 4352K51) was placed at the outlet to measure theflowrate. The inlet and outlet pressures were measured by two Honeywellpressure transducers (Part No. ABPDANT005PGAA5). The motor speed wasmeasured with motor's integrated hall-effect sensor. A mixture of waterand glycerol with a mass ratio of 54 to 46 was circulated in the loop torepresent the density (1.12 [g/mL]) and viscosity (3.56 [mPaS]) of blood[14]. The MCS prototype was controlled to run at several constant speedsagainst various pressure differences, which was achieved by a resistanceclamp (not shown in the figure). The flowrate and pressure differencewere chosen according to human-heart operating conditions and range from0 to 6 [LPM] and 0 to 120 [mmHg], respectively. All electronic controlschemes and data collection were implemented using MATLAB Simulink andan xPC Target machine using a PCI-6229 National Instrument DAQ board.

CFD Setup. To solve the fluid-structure interaction (FSI) problem, aparallelized computational framework was employed that was previouslydeveloped for simulating biological systems that involve largedeformations [28-31]. In this partitioned framework, the flow was solvedby using a Cartesian grid based on a sharp-interface direct-forcingimmersed-boundary method. While in the current case, the structures wereconsidered as rigid parts and their transient kinematics were prescribedaccording to Kinematics of Sliding Vane section.

In the simulation, the flow domain was represented by a 79×40×19 cm³rectangular bounding box and was divided by a 263×126×60 uniformCartesian grid with Δx, Δy and Δz being about 3.0×10−4 cm. The densityand dynamic viscosity of the blood are, ρ=1.0 [g/cm³] and μ=0.005 [Pas], respectively. Each cycle had a time duration of T=0.6 s and the timestep used in the flow solver is Δt=5.0×10-5 s. Pressure boundaryconditions were prescribed at both the inlet and outlet.

Laminar flow. When fluid is blood, the flow may be laminar flow based onthe following: averagely blood density ρ=1056 kg/m³, blood dynamicviscosity μ=3.5 cP=3.5e-3 PaS, the diameter of inlet/outlet d=11e-3 m,average flow rage Q=5 lpm=1.67e-5 m³/s,so Reynolds=4 ρQ/πμd=582<2300.

Meanwhile, in order to accelerate the simulation, a two-dimensionaldomain decomposition was applied and 9 and 5 was used uniform subdomainsin y- and z-directions respectively, which yields the deployment of atotal number of 45 CPU cores. The simulation used the high-performancecomputing facility of Wiegand Advanced Visualization Environment atSanta Clara University (SCU WAVE HPC).

Results

MCS Pump Performance Characterization. A series of experiments wereconducted with various operating conditions. The motor speed varied from100 [RPM] to 300 [RPM] while the system pressure difference was adjustedby the clamp from 0 to 120 [mmHg].

The resulting pressure difference versus flowrate curves of the MCSprototype are shown in FIG. 6 . Non-positive displacement feature can benoted that the flowrate decreases as the load pressure across the pumpincreases. Compared with prevailing hydrodynamic rotary VADs, such asHeartware, HeartMate2 and CH-VAD [19], the sliding vane MCS pump hasflatter HQ curves and can be regarded as positive displacement pump withleakage. The flatness of the HQ curves shown in FIG. 6 appear to be dueto the positive displacement pumping architecture.

The leakage is represented in FIGS. 7A-7C by a gap depicted in box B)between rotary cylinder and flow straightener's flow separator, whichprovides a leakage pathway from outlet directly to inlet, and a gap(depicted in box C) between vane and housing wall, which providesleakage from one chamber to the other. Nonetheless, fairly linearrelationships between pressure and flowrate are apparent (R²>0.9700) andcorresponding linear least squares regression fittings are obtained asfollows (with Q, w, and ΔP have units of [LPM], [RPM], and [mmHg]respectively)

Q(w| ₁₀₀ ,ΔP)=−1.045×10⁻² ΔP+1.9095,R ²=0.9762  (12)

Q(w| ₁₅₀ ,ΔP)=−9.01×10⁻³ ΔP+3.2570,R ²=0.9804  (13)

Q(w| ₂₀₀ ,ΔP)=−9.34×10⁻³ ΔP+4.2960,R ²=0.9783  (14)

Q(w| ₂₅₀ ,ΔP)=−9.10×10⁻³ ΔP+5.4050,R ²=0.9702  (15)

Q(w| ₃₀₀ ,ΔP)=−1.032×10⁻² ΔP+6.6086,R ²=0.9778  (16)

Theoretically, with specifications shown in Table 1, the MCS pump is apositive displacement pump and has a displacement of 24.8 [mL/rev]. Thetheoretical output flowrate with respect to rotary speed is plotted as asolid line in FIG. 8 . No-leakage flowrates of the experimental MCSprototype pump under different operating speeds can be acquired byextrapolating the above linear fittings (dashed lines) and intersectingwith the y-axis. The intersect points are depicted as open squares inFIG. 8 . The no-leakage flowrates under 100 [RPM] to 300 [RPM] show thatthe prototype has a fairly linear displacement pumping ability withrespect to rotary speed.

The mathematical model developed previously for displacement calculationmatches well with experimental displacement result (93.10%).

V _(disp:experimental) /V _(disp:theoretical)=23.09/24.80=93.10%  (17)

Pulsatile Flow. To illustrate the MCS pump's pulsatility, an estimatorof the MCS flowrate is needed. A first-order polynomial equation with ΔP[mmHg], and ω [RPM] as input variables was found to match well with theexperiment data presented previously (FIG. 6 ) and is used here toestimate flowrate Q(t)[LPM]:

Q _(est)(t)=a ₁ ΔP(t)+a ₂ω(t)+a ₃  (18)

where parameters (a₁, a₂, a₃)=(−9.644×10⁻³, 2.309×10⁻², −3.233×10⁻¹).Real time pressure sensor data and motor speed data were collected andresampled due to the sensors' different sampling frequencies before thedata were plugged into Eqn. 18. The estimated flowrate, 0 est, was thencompared with the theoretical flowrate. These flowrate curves underseveral operating conditions are plotted in FIGS. 9A-11B.

As the figures illustrate, the estimated instantaneous flowrate of theprototype MCS pump shows pulsatile behavior. Flowrate varies noticeablyas the rotary angle increments. Since the first-order polynomial fittingfunction to calculate instantaneous flowrate is derived using the datain FIG. 6 , the discrepancy between the average experimental (fitting)flowrate and the average theoretical flowrate is consistent with thedata in FIG. 8 .

Experimental tests were conducted to characterize the MCS pump prototypeand to validate the developed model. H-Q curves of the proposed MCS pumpwere experimentally measured.

The leakage could happen between the rolling cylinder and the flowstraightener (see FIG. 7B). A mechanism like a wiper blade between themcould reduce leakage through this pathway. In certain applications, asmall degree of leakage may be designed in, to control the overall shearapplied to the traversing fluid, balancing net output against shearstress and stress accumulation.

Another possible leakage source is the gap between the vane and the wall(see FIG. 7C). Although other solutions to Eqn. 1 exist to allowconstant contact between sliding vane end and the wall, manufacturetolerance still exists, leading to gaps. Smaller gaps will lead to lessbackflow leakage, thus increasing the pump efficiency. However, thiswould also contribute to higher shear stresses onto blood, causing blooddamage. Alternative vane designs are provided (FIGS. 12A-12C) tointroduce a gap for reducing shear stress on the fluid but to retain thepump performance as a positive displacement pump.

The proposed MCS pump, mathematically and experimentally, showed a morephysiologic pulsatile flow generation, compared to the attenuated ornon-pulsatile flow generated from prevailing rotary VADs. A flowrateestimator using polynomial fittings was adopted.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of skill in the artto which the disclosed invention belongs. Publications cited herein andthe materials for which they are cited are specifically incorporated byreference.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

REFERENCES

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1. A valveless pump for pulsatile fluid flow comprising: (i) a housingwith a central circular opening defined by a peripheral wall; an inletin fluid communication with the central circular opening; and an outletin fluid communication with the central circular opening; and (ii) asingle vane within the central circular opening; wherein the vane isconfigured to rotate about an axis offset from a central axis of thecentral circular opening without substantially contacting the peripheralwall of the housing.
 2. The valveless pump of claim 1, wherein the vaneis a one-piece vane.
 3. The valveless pump of claim 1, wherein the vanecomprises two ends, and wherein the valveless pump comprises a gapbetween each of the two ends and the peripheral wall.
 4. The valvelesspump of claim 3, wherein the gap is about 10 μm to 5 mm long, asmeasured from a proximal vane end to the peripheral wall.
 5. Thevalveless pump of claim 1, comprising a motor operably connected to thevane.
 6. The valveless pump of claim 1, comprising an electric motor, anelectromagnetic motor, a passive magnetic motor, or an active magneticmotor, hydraulic motor, or acoustic motor, operably connected to thevane.
 7. The valveless pump of claim 1, comprising a motor operablyconnected to a rotary cylinder comprising a slot wherein the vane isslidably received in the slot, wherein a central axis of the rotarycylinder is offset from the central axis of the central circularopening.
 8. The valveless pump of claim 7, the slot that runs from oneside of a peripheral wall to an opposite side of the peripheral wall ofthe cylinder and through the central axis of cylinder and has shape thatconforms to the shape of the vane.
 9. The valveless pump of claim 1,comprising a motor operably connected to a rotary cylinder.
 10. Thevalveless pump of claim 9, wherein the rotary cylinder is configured torotate about a central axis of the rotary cylinder.
 11. The valvelesspump of claim 1, wherein the vane has two ends and wherein each end isrounded.
 12. A system comprising the pump of claim 1, optionally two ormore pumps of claim
 1. 13. The system of claim 12, further comprising aninlet port and an outlet port, wherein the inlet port is reversablyconnected to and in fluid communication with a fluid supply tube and theoutlet port is reversably connected to and in fluid communication with afluid exit tube.
 14. The system of claim 13, wherein the system is aclosed system configured to provide circulatory fluid flow.
 15. Thesystem of claim 12, wherein in use the pump, optionally each pump of thetwo or more pumps, is configured to provide constant fluid displacementvolume in the range between about 5 mL and about 70 mL per revolution.16. The system of claim 12, wherein in use the pump, optionally eachpump of the two or more pumps, is configured to provide fluiddisplacement at variable flow rates and variable fluid pressure. 17.-21.(canceled)
 22. A method for pulsatile flow of an incompressible fluidcomprising pumping the fluid through the pump of claim
 1. 23.-34.(canceled)
 35. A mechanical circulatory support device comprising a pumpfor pulsatile fluid flow comprising: (i) a housing with a centralcircular opening defined by a peripheral wall; an inlet in fluidcommunication with the central opening; and an outlet in fluidcommunication with the central opening; and (ii) a single vane withinthe central opening; wherein the vane is configured to rotate about anaxis offset from a central axis of the central circular opening withoutsubstantially contacting the peripheral wall of the housing. 36.-37.(canceled)
 38. A method of mechanically supporting a ventricular orheart function in a subject comprising connecting a pump to thecardiovascular system of the subject, the pump comprising: (i) a housingwith a central circular opening defined by a peripheral wall; an inletin fluid communication with the central opening; and an outlet in fluidcommunication with the central opening; and (ii) a single vane withinthe central opening; wherein the vane is configured to rotate about anaxis offset from a central axis of the central circular opening withoutsubstantially contacting the peripheral wall of the housing. 39.-47.(canceled)
 48. The system of claim 12, wherein the system is anextracorporeal membrane oxygenation system or a cardiopulmonary bypasssystem.